The present invention relates to a touch input device for inputting information by touching a touch panel.
A personal computer, a portable transmission device, other personal information processing devices, etc. perform text processing, graphic processing, etc. by using a variety of input devices, such as a keyboard, a mouse, and a digitizer.
The input devices are input device as interfaces according to the expansion of PC use, and the products cannot be handled by using only a keyboard and a mouse. The input devices are being developed owing to the need in which the input devices are simple and less in a mal-operation and anyone can easily perform input and perform text input directly while carrying the input devices.
In particular, there has been known a touch panel which is simple and less in a mal-operation and which enables a user to perform a desired command by only touching a panel so that the user can perform input directly. There are various types of touch panels in the detection method, structure, performance, etc. of the touch panel. That is, the touch panel can be basically classified into a resistive film method, a capacitance method, a ultrasonic wave method, a light (infrared) sensor method, an electronic induction method, etc.
The resistive film method touch panel is the most frequently used touch panel and is also called a decompression method touch panel for sensing pressure. The resistive film method touch panel includes an upper and lower plate structure having two layer. When the touch panel is touched by applying pressure, the upper and lower plates are brought in contact with each other, electricity flows, and the electricity is sensed. The ultrasonic wave method touch panel, the light (infrared) sensor method touch panel, the electronic induction method touch panel, etc. are complicated and expensive, and they are not suitable for small-sized touch panel, but are limitedly used in fixed and large-scale panels.
Meanwhile, the capacitance method touch panel is also called an electrostatic or constant voltage method. The capacitance method touch panel is based on the fact that an electric field is formed when an electric current is made to flow on a surface of the panel. When an electric current is made to flow toward the center of a square panel from the four points of the square panel, the fact that the electric current becomes weak farther from the points is sensed and a location to be touched is sensed by measuring the sensed values.
In this touch panel input device, a user can input a command by touching the touch panel by using his finger. If a user's finger touches the touch panel, however, there are problems in that the touch panel is contaminated or damaged by a sharp nail, etc. and precise manipulation is difficult. A touch pen or a stylus pen is used as a touch input device for solving the problems.
In the resistive film method, a touch panel has only to be touched by applying pressure to the touch panel. The tip of a touch pen as a touch panel input device has only to be formed in the body having a common long shape. However, the capacitance method touch panel cannot use a resistive film method touch pen and must use a conductive touch pen that is able to be used only in a capacitance method touch panel.
A conventional capacitance method touch pen includes a touch tip made of a conductive material and provided at the end of a body 10.
The touch tip is made of a conductive rubber material or a conductive fiber material.
The touch tip has a cylindrical shape and inevitably has a large diameter. This is because a minimum cross area for sensing a change of capacitance between the touch tip and an electrode formed on the surface side of the panel is necessary. That is, if the touch tip has a small cross area, the sensing precision of a sensor must be increased. However, malfunction due to noise resulting from environmental factors, for example, moisture in the atmosphere, other external dielectric alien substances and an error due to a temperature drift are likely to occur, and power consumption for a sensing circuit is sharply increased. Accordingly, in order to sense a touch on the touch tip under sensing precision capable of excluding external noise, the touch tip inevitably has a large cross area. As a result, the size of the touch panel input device is inevitably increased. As described above, in order to increase the cross area, the contact area of the touch tip and the touch panel may be maximized by cutting the front end of the touch tip diagonally.
Furthermore, if a touch pen is used instead of a finger, the contamination of a touch panel and damage to the touch panel can be slightly reduced. If a task, such as a drag, is performed in the state in which a touch tip touches or has touched the touch panel, however, there are problems in that the touch panel is inevitably damaged and it is difficult to use the touch panel softly.